Purpose <p>Patients with bimodal auditory stimulation represent an expanding group of cochlear implant users in many countries. The hearing results reported in the literature for subjects with bimodal hearing are controversial and often only evaluate hearing aids that are simply synchronized with their cochlear implant (“synchronized” regulation) and sometimes even adapted independently of the cochlear implant (“classic” regulation). This study aims to verify that the innovative “symbiotic'' regulation of the cochlear implant with an integrated hearing aid and dedicated fitting formula allows to achieve adequate rehabilitative hearing levels.</p> Material and methods <p>Thirty adult patients (12 females and 18 males; age range: 18–69&#xa0;years) with bimodal hearing have been enrolled in a one-year study and divided into three groups of ten subjects for each of the regulation modes (“classic”, “synchronized” and “symbiotic”) applied to fit the cochlear implant and the hearing aid. Statistical analysis of the demographic characteristics and hearing outcomes observed in the three groups was conducted using the R statistical software.</p> Results <p>For all subjects, the use of the “symbiotic” regulation approach with a dedicated bimodal regulation formula and integrated hearing aid allowed significantly better hearing performances (p &lt; 0.05) compared to those obtained to either the “classic” or the “synchronized” regulations.</p> Conclusion <p>The “symbiotic” bimodal fitting formula provides significant hearing benefits compared to “classic” and “synchronized” regulation and it proves to be the ideal adjustment and coupling modality between a cochlear implant and a contralateral integrated hearing aid in bimodal listeners.</p>